In a Long Term Evolution (LTE for short) system, communication is implemented in a centralized network control manner, that is, uplink and downlink signals of a terminal are sent and received under control of the network. Communication between terminals is forwarded and controlled by the network. There is no direct communication link between the terminals. Signal transmission between the terminal and the network in this manner may be referred to as device to network (D2N for short) transmission for short. In other words, as shown in FIG. 1A, services such as a voice and a signal between two terminals are exchanged by using a base station (common base stations or evolved NodeBs) where the two terminals are respectively located and a core network.
In future development of a mobile communications system, device to device (D2D for short) communication technologies are introduced to better meet a user requirement and improve efficiency of information exchange between devices. That is, as shown in FIG. 1B, neighboring terminals may transmit a signal in a short-distance range by using a direct link, with no need to use a central node (such as a base station) for forwarding.
The D2D communication technologies have the following advantages.
1. A short-distance direct communication manner of a terminal can achieve a relatively high signal transmission rate, a relatively low delay, and relatively low power consumption.
2. Widely distributed communication terminals in a network and a short distance characteristic of a D2D communication link are used, so that a spectrum resource may be effectively used.
3. A D2D direct communication manner satisfies a local signal sharing requirement of a wireless end-to-end service or the like, and a signal service with flexible adaptability is provided.
4. In D2D direct communication, a large quantity of communication terminals that are widely distributed in a network can be used to expand a network coverage range.
In an LTE-D2D communications system, because a frequency hopping technology is used, a frequency resource used for transmitting a physical uplink shared channel (PUSCH for short) conflicts with a frequency resource that is allocated by a system to D2D user equipment for data transmission, and this affects data transmission between D2D user equipments.